1. Field of the Invention
The invention relates to a wheel assembly with an in-wheel motor in which a motor for driving a wheel is arranged within the wheel.
2. Description of the Related Art
Japanese Patent Application Publication No. JP-A-2005-335623, for example, describes a related wheel assembly with an in-wheel motor in which oil is supplied for cooling the motor and lubricating a reduction mechanism. In the invention described in Japanese Patent Application Publication No. JP-A-2005-335623, an oil tank is arranged farther toward a vehicle outside than a lower ball joint.
In the foregoing wheel assembly with an in-wheel motor, the limited space within the wheel must be used to house the motor, the reduction mechanism, an oil pump, the oil tank, and an oil circulation passage. The arrangement of these main constituent elements is preferably such that they do not restrict the design of the suspension. That is, by arranging these main constituent elements as close to the vehicle outside as possible within the wheel, the weight of the knuckle and the like can be reduced and ample space is left on the vehicle inside within the wheel for the design of the suspension.
With respect to this, in the invention described in Japanese Patent Application Publication No. JP-A-2005-335623 above, the oil tank is arranged farther toward the vehicle inside than the lower ball joint, which greatly restricts the design of the suspension.
On the other hand, a structure in which the oil tank is arranged farther toward the vehicle outside than the lower ball joint is advantageous in terms of the degree of freedom it offers with respect to the design of the suspension. However, there is not much space due to the relationship with the brake disc so the arrangement itself is difficult. Also, even if the arrangement is possible, oil that drips from the oil tank in the unlikely event of an oil leak or when the oil is being changed may drip onto the brake disc and reduce its performance.